oxygen

Resin printing, it can be messy but you get really great resolution thanks to the optical nature of curing the sticky goo with light from a projector. Soon it will have a few more notches in its belt to lord over its deposition cousins: speed and lack of layers. A breakthrough in resin printing makes it much faster than ever before and pretty much eliminates layering from the printed structure.

The concept uses an oxygen-permeable layer at the bottom of the resin pool. This inhibits curing, and apparently is the source of the breakthrough. The resin is cured right on the border of this layer and allows for what is described as a continuous growth process rather than a layer-based approach. One of the benefits described is no need for resin to flow in as the part is extracted but we’re skeptical on that claim (the resin still needs to flow from somewhere). Still, for us the need to work with resin which is expensive, possibly messy, and has an expiry (at least when compared to plastic filament) has kept deposition as a contender. The speed increase and claims of strength benefits over layer-based techniques just might be that killer feature.

The technology is coming from a company called Carbon3D. They are branding it CLIP, or Continuous Liquid Interface Production. After the break you can see a video illustration of the concept (which is a bit too simple for our tastes) as well as a TED talk which the company’s CEO, [Joseph Desimone] gave this month. Of course there is also the obligatory time-lapse print demo.

So what do you think: game changer or not, and why do you feel that way? Let us know in the comments.

We are fascinated by the hybrid rocket engine which [Ben Krasnow] built and tested in his shop. It is actually using a hollow cylinder of acrylic as the fuel, with gaseous oxygen as an oxidizer. We’re already quite familiar with solid rocket propellant, but this hybrid approach is much different.

When a rocket motor using solid propellant is lit it continues to burn until all of the fuel is consumed. That is not the case with this design. The acrylic is actually burning, but if the flow of oxygen is cut off it will go out and can be ignited later. This also opens up the possibility of adjusting thrust by regulating the pressure of the oxygen feed.

[Ben] milled the test rig in his shop. It’s a fat acrylic rod through which he bored a hole. There are two aluminum plates which complete either end of the chamber. The intake has a fitting for a valve which connects to the oxygen tank. There is a nozzle on the outflow end. Check out the video after the break to see a full description. You’ll also get a look at the toll the combustion heat takes on the rig.

[Mike] is building his own Pulse Oximeter which uses light to measure the oxygen saturation in blood. One collateral benefit of this measurement is that pulse rate can be calculated from the same data. The parts used for the detector include a red LED, infrared LED, and a TSL230R light intensity measuring chip. As explained in the video above, each LED is shined through the tip of your finger and onto the light sensor. The IR LED is used as a baseline and compared to the red LED, which has some of its intensity absorbed by the red blood in your finger. This is a pretty approachable biometric concept so you may want to start here before moving on to more involved biometric interfaces.